I have a Maytag Topload Washer that makes a grinding noise when it Agitates and I need the Service Manual (if available) to help with troubleshooting.The Lower Agitator isn't stripped, therefore could it be the Belt or Transmission?

I agree with AJ. Check the pump first. They are a well known problem. Look at the pulley on the pump.If you see a shiny piece of corrugated metal sticking up between the pulley and the pump base replace the pump.